Alabama was one of only sixteen States that permitted commercial hazardous waste landfills. From 1985 through 1989, the tonnage of hazardous waste received per year more than doubled. Of this, up to 90 percent of the hazardous waste was shipped in from other States. In response, Alabama imposed a fee of $97.60 per ton for hazardous waste generated outside Alabama compared with a fee of $25.60 per ton for hazardous wastes generated within Alabama. Chemical Waste Management, Inc., which operates a commercial hazardous waste land disposal facility in Emelle, Alabama, filed suit asserting that the Alabama law violated the Commerce Clause of the U.S. Constitution.